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  2. Masahiro KOHIRA

Masahiro KOHIRA

  (小平 將裕)

Profile Information

Affiliation
Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency
J-GLOBAL ID
202001017096347690
researchmap Member ID
R000007241

Research Areas

 2

Research History

 8
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Education

 3

Awards

 1

Papers

 9
  • Masahiro I. Kohira, Hiroyuki Kitahata, Nobuyuki Magome, Kenichi Yoshikawa
    PHYSICAL REVIEW E, 85(2), Feb, 2012  Peer-reviewed
    An oscillatory system called a plastic bottle oscillator is studied, in which the downflow of water and upflow of air alternate periodically in an upside-down plastic bottle containing water. It is demonstrated that a coupled two-bottle system exhibits in- and antiphase synchronization according to the nature of coupling. A simple ordinary differential equation is deduced to interpret the characteristics of a single oscillator. This model is also extended to coupled oscillators, and the model reproduces the essential features of the experimental observations.
  • Shun N. Watanabe, Takafumi Iwaki, Masahiro I. Kohira, Nobuyuki Magome, Kenichi Yoshikawa
    CHEMICAL PHYSICS LETTERS, 511(4-6) 447-451, Aug, 2011  Peer-reviewed
    We observed the photophoresis of smoke particles in a small focal laser beam under micro-gravity, exerted in an airplane, to avoid air convectional flow due to buoyancy. We measured the motion of smoke particles and found that the particles exhibit negative photophoresis under the suppression of the convection. Based on the distribution of velocity of negative photophoresis, it is shown that the photophoretic velocity is proportional to the laser power applied for the particle. We discuss the mechanism in terms of the radiometric force. (C) 2011 Elsevier B.V. All rights reserved.
  • Masahiro I. Kohira, Nobuyuki Magome, Shin-Ichiro Mouri, Hiroyuki Kitahata, Kenichi Yoshikawa
    INTERNATIONAL JOURNAL OF UNCONVENTIONAL COMPUTING, 5(1) 103-111, 2009  Peer-reviewed
    When a plastic bottle with water is placed upside-down with a thin pipe at its head. limit-cycle oscillation call be observed. A simple differential equation can reproduce the properties of this oscillation. In the present study, a three-coupled-oscillator system is investigated experimentally and numerically. The behavior of the three coupled oscillators with frustration is interesting from the viewpoint of mathematical physics, and with all increase in size, this system should be helpful in unconventional computing, such Lis in, for example, optimization problems.
  • Masahiro I. Kohira, Nobuyuki Magome, Hiroyuki Kitahata, Kenichi Yoshikawa
    AMERICAN JOURNAL OF PHYSICS, 75(10) 893-895, Oct, 2007  Peer-reviewed
    The oscillatory flow of water draining from an upside-down plastic bottle with a thin pipe attached to its head is studied as an example of a dissipative structure generated under far-from-equilibrium conditions. Mode bifurcation was observed in the water/air flow: no flow, oscillatory flow, and counter flow were found when the inner diameter of the thin pipe was changed. The modes are stable against perturbations. A coupled two-bottle system exhibits either in-phase or anti-phase self-synchronization. These characteristic behaviors imply that the essential features of the oscillatory flow in a single bottle system can be described as a limit-cycle oscillation. (c) 2007 American Association of Physics Teachers.
  • Akihiro Isomura, Nobuyuki Magome, Masahiro I. Kohira, Kenichi Yoshikawa
    CHEMICAL PHYSICS LETTERS, 429(1-3) 321-325, Sep, 2006  Peer-reviewed
    To identify the optimum conditions for the optical trapping of a droplet under microgravity, we theoretically analyzed the efficiency of trapping with counter laser beams. We found that the distance between the two foci is an important parameter for obtaining stable trapping conditions. We also performed an optical trapping experiment with counter laser beams under microgravity. The experimental results correspond well to the theoretical prediction. (c) 2006 Elsevier B.V. All rights reserved.
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Misc.

 19
  • MAGOME Nobuyuki, ISOMURA Akihiro, AGLADZE Konstantin, KOHIRA I. Masahiro, MIURA Keitaro, DATTA Alokmay, YOSHIKAWA Kenichi
    25(4) 791-791, Oct 30, 2008  
  • Watanabe Shun N., Yoshikawa Kenichi, Iwaki Takafumi, Kohira Masahiro I., Magome Nobuyuki
    (22), Mar, 2006  
    Photophoresis, which is a light action to a particle, has been experimented under a parallel beam. Under a convergent beam, another light action "optical trap" is well known. Photophoretic force field under a convergent beam is very important information for making photophoretic trap, but have never been studied. In present study, we observed photophoresis of liquid smoke particles both on a small convergent laser beam and on a parallel beam, under the micro-gravity condition in order to avoid the convectional flow due to buoyancy. Experimental results indicate that photophoretic velocity scales as 0.43 about 1/2 power of the radiation intensity. That are new results for photophoretic experiments. In addition, we give a theoretical treatment to derive the power to be 1/2, by taking into account of the effect of a Marangoni convection.Meeting sponsors: The Science Council of Japan, The Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (ISAS)(JAXA)
  • Isomura Akihiro, Kohira Masahiro I.
    Meeting Abstracts of the Physical Society of Japan, 60 336-336, 2005  
  • Watanabe Shun, Iwaki Takafumi, Kohira Masahiro I.., Magome Nobuyuki
    Meeting Abstracts of the Physical Society of Japan, 60 239-239, 2005  
  • Watanabe Shun, Matsuda Norihiko, Magome Nobuyuki, Kohira Masahiro, Sumino Yutaka, Isomura Akihiko, Yoshikawa Kenichi
    Meeting Abstracts of the Physical Society of Japan, 59 250-250, 2004  
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Professional Memberships

 2
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